During the next year a major emphasis will be placed on using the methods developed in the rat for evaluating capillary permeability and flow to study the effects of pharmacological agents on these parameters. The rat model system will be a great value in this work over the 15O-water system in the monkey because in the monkey several months are required to complete an adequate dose response curve, where as in the rat this can be accomplished in 2 or 3 days. Major findings in the rat will be confirmed using the monkey model. These experiments will be carried out as proposed in the original grant application and do not represent a change in direction.